The broad objective of this study is to understand the mechanisms used by the various types of kidney cells to accomplish certain functions and to determine what are the alterations at the cellular level accompanying certain disease states which affect these renal functions. This study proposes to alter certain physiological conditions in animals, or to administer specific drugs to animals, and to correlate the physiological and pathological state thus produced with renal morphology utilizing descriptive techniques such as light microscopy, histochemistry, transmission electron microscopy as well as x-ray microanalysis. Studies will concentrate on two areas. 1. Various model systems of acute renal failure will be utilized to correlate morphological changes with documented altered physiological state. 2. Electron probe microanalysis will be under taken of the kidney with emphasis on the renal medulla of normal and diabetes insipidus rats in an attempt to characterize the ion content of various cell compartments. Results of those studies should prove useful in obtaining a deeper understanding of renal diseases and perhaps lead to a more rational approach to therapy of acute renal failure.